This invention relates to an improved process for preparing 1-organothio-aldoxime compounds. More particularly, this invention is directed to a method of preparing 1-organothio-aldoxime compounds by halogenating the aldoxime in an aqueous sovlent containing from 5 to 75 percent by weight of a linear or cyclic polyhydric alcohol containing two or more hydroxyls and having from 2 to 20 carbon atoms, and reacting the resulting 1-haloaldoxime with the sodium salt of a mercaptan.
1-Organothio-aldoxime compounds and their preparation by the chlorination of an aldoxime followed by reaction with a sodium mercaptide are well known. U.S. Pat. Nos. 3,658,869 and 3,535,361 disclose a two-step preparation of organothio-aldoxime compounds by chlorination of an aldoxime in aqueous medium followed by reaction of the resultant chloroacetaldoxime with a thiol. The main drawback of such prior art processes is low yield of the desired product. U.S. Pat. No. 3,752,841 discloses an improvement of the basic process in which the reaction medium is dimethylformamide or an aqueous mixture containing at least ten weight percent dimethylformamide. This process also suffers from a number of inherent disadvantages. The separation problems of the 1-hydrocarbylthioaldoxime compounds are complicated by the use of the dimethylformamide since these compounds are very soluble in dimethylformamide. This makes it necessary to use costly, elaborate and cumbersome purification procedures, such as distillation, solvent extraction and the like, to isolate the final product.
It is, therefore, the object of this invention to provide a more effective process for preparing 1-organothioaldoxime compounds in exhanced yields.